Feasibility of Power and Methanol Production by an Entrained-Flow Coal Gasification System

Sustainability metrics, a cradle-to-gate life cycle assessment, and a technoeconomic evaluation are presented for an optimized entrained-flow coal oxy-combustion plant with carbon capture to produce power and methanol. The aim of the study is to assess the feasibility of coproducing methanol in a coal-based power plant with an entrained-flow coal gasification system. Coal-based methanol, as an attractive liquid transportation fuel as well as an essential intermediate chemical feedstock, can fill a possible gap between declining fossil fuel supplies and movement toward the hydrogen economy. Within the plant, first the coal is fed to a pyrolysis reactor, and then the volatile matter is fed into an oxy-combustion reactor while the char is gasified in an entrained-flow gasifier. The remaining char is gasified. The heat is used to produce electricity, while the syngas is converted to methanol. The integral plant, consisting of an air separation unit, oxy-combustion of coal, gasification of char, electric power production, carbon capture, and conversion to methanol, was designed and optimized using the Aspen Plus package. The optimization includes the design specification of process heat integration using an energy analyzer toward a more efficient clean-coal technology with methanol production. The plant uses 500 metric tons (MT) of Powder River Basin coal and 2231.03 MT of air per day and produces 32.76 MWh of electric power and 207.99 MT of methanol per day. The total amount of captured CO₂ is 589.75 MT/day, and nitrogen is also produced at 1309.33 MT/day. A multicriteria decision matrix consisting of economic indicators as well as the sustainability metrics is developed to assess the feasibility of the extended plant. Methanol production in addition to power production may improve the overall feasibility of coal-powered plants

Influence of Subenvironmental Conditions and Thermodynamic Coupling on a Simple Reaction-Transport Process in Biochemical Systems

Living systems must continuously receive substrates from subenvironment, and the population metabolic rate model is affected on this flow of substrates to be metabolized, its relevant variables, and the rate at which operates. This study focuses on the influences of resistances and bulk phase factors with in the subenvironment and by thermodynamic coupling on reaction-transport processes representing a simple enzymatic conversion of a substrate to a product. Thermodynamic coupling refers to mass flow, or a reaction velocity that occurs without or opposite to the direction imposed by its primary thermodynamic driving force. We considered the effects of (i) subenvironment resistances for the heat and mass flows of reacting substrate in the form of the ratios of Sherwood to Nusselt numbers, (ii) the subenvironment bulk phase temperatures and concentration of substrate, and (iii) the cross-coefficients responsible for the induced effects due to the thermodynamic coupling. In order to study these effects, the thermodynamically coupled balance equations using the first order simple elementary reaction are derived and solved numerically. In the balance equations, the linear phenomenological equations are used by assuming that the system is in the vicinity of global equilibrium. The overall results show that the subenvironment factors and cross-coefficients due to thermodynamic coupling may have considerable effects on reaction-transport processes